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TPS92641: PWM Dimming Ratio

Hirotsugu Kobayashi
Mastermind 8485 points
Part Number: TPS92641

Hi, team.

What kind of condition is PWM Dimming Ratio of a data seat?

In case of Standard PWM dimming, what kind of dimmer frequency and smallest PWM width is 2500:1?

In case of Shunt PWM dimming, what kind of dimmer frequency and smallest PWM width is 20000:1?

BR

  • 0
    TI__Mastermind 25500 points

    Hello Hirotsugu,

    You need to take datasheet specs such as those with a grain of salt. I honestly do not know what conditions they used to generate those specs.

    The reality of it is that the minimum pulse width for either is determined by the UDIM-HG/SDIM-SDRV delays specified in the datasheet. The of course with UDIM the rising/falling times are determined by v=Ldi/dt and with SDIM the rising/falling times are determined by parasitics. Both are very dependent on VIN, VOUT, current, etc... But basically the lower the PWM frequency the higher the dimming range.

    I might be able to give you an estimate of both if you could let me know the current, input/output voltages, and LED current. But I'm guessing those specs from the datasheet are likely in the 120Hz to 250Hz PWM dimming range.

    Regards,

    Clint